Ionizing radiation stable thermoplastic composition, method of making, and articles formed therefrom

Abstract

A thermoplastic composition comprises a polycarbonate that is not aryl carboxylate end-capped, and an aryl carboxylate end-capped polycarbonate of formula: Ar 1 —C(O)—O-(-L-) m -O—C(O)—A 1 wherein each Ar 1 is independently an aryl group, -(-L-) m - is a polycarbonate linking group with m units of linking unit L, and m is at least one; wherein the aryl carboxylate end-capped polycarbonate has aryl carboxylate end groups present in the thermoplastic composition in an amount of 0.01 to 500 mmol/Kg based on the combined weights of the polycarbonate that is not aryl carboxylate end-capped, and the aryl carboxylate end-capped polycarbonate, and wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of the aryl carboxylate end-capped polycarbonate, the polycarbonate, and less than or equal to 1.0 percent total weight of aliphatic diol, a mold-release agent, and an antioxidant has, after exposure to a total gamma radiation dose of 81 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 24.5, when compared to the unexposed molded article. A method for preparing the aryl carboxylate end-capped polycarbonate that is not aryl carboxylate end-capped, and thermoplastic composition, an article prepared from the thermoplastic composition, are also disclosed.

1. A thermoplastic composition comprising:
 a polycarbonate that is not aryl carboxylate end-capped, and 
 an aryl carboxylate end-capped polycarbonate of formula:
   Ar 1 —C(O)—O-(-L-) m -O—C(O)—Ar 1   
 
 wherein each Ar 1  is independently an aryl group, -(-L-) m - is a polycarbonate linking group with m units of linking unit L, wherein L consists essentially of carbonate units wherein m is at least one, or a combination of carbonate units with poly(arylene ether) units, soft block units, or a combination comprising at least one of these, wherein m is 2 to 500 and at least one L is a carbonate unit; 
 wherein the aryl carboxylate end-capped polycarbonate has aryl carboxylate end groups present in the thermoplastic composition in an amount of 0.01 to 500 mmol/Kg based on the combined weights of the polycarbonate that is not aryl carboxylate end-capped, and the aryl carboxylate end-capped polycarbonate, and 
 wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of the aryl carboxylate end-capped polycarbonate, the polycarbonate that is not aryl carboxylate end-capped, and less than or equal to 1.0 percent total weight of aliphatic diol, a mold-release agent, and an antioxidant has, after exposure to a total gamma radiation dose of 81 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 24.5, when compared to the unexposed molded article. 
 
     
     
       2. The thermoplastic composition of  claim 1 , wherein the aryl carboxylate end groups are present in the aryl carboxylate end-capped polycarbonate in amount of 0.01 to 10 mole-percent based on the total number of moles of linking unit L present in the aryl carboxylate end-capped polycarbonate. 
     
     
       3. The thermoplastic composition of  claim 1 , wherein the aryl carboxylate end-capped polycarbonate is present in an amount of 1 to 80 wt %, based on the total weight of the polycarbonate that is not aryl carboxylate end-capped, and aryl carboxylate end-capped polycarbonate, with the proviso that the amount and type of aryl carboxylate end-capped polycarbonate is selected so that the overall concentration of aryl carboxylate end groups is less than or equal to a molar concentration of 500 millimoles per kilogram (mmol/Kg), and is greater than or equal to 0.01 mmol/Kg, of the total weight of the polycarbonate that is not aryl carboxylate end-capped, and aryl carboxylate end-capped polycarbonate. 
     
     
       4. The thermoplastic composition of  claim 1 , wherein each Ar 1  is independently an unsubstituted C 6 -C 20  aryl group, or substituted C 6 -C 20  aryl group. 
     
     
       5. The thermoplastic composition of  claim 1 , wherein when-(-L-) m - consist essentially of carbonate units, m is 1 to 500. 
     
     
       6. The thermoplastic composition of  claim 1  wherein the poly(arylene ether) unit has the formula:
   —(—Ar 2 —X—Ar 2 —O—) n —Ar 2 —X—Ar 2 — 
 wherein n is 0 to 200, wherein each Ar 2  is independently a substituted C 6 -C 20  arylene group or unsubstituted C 6 -C 20  arylene group; and wherein X is a bridging radical having one or two atoms that separate the Ar 2  groups. 
 
     
     
       7. The thermoplastic composition of  claim 1 , wherein soft block units consist essentially of polysiloxane units, polyalkylene oxide units, poly(alkylene ester) units, polyolefin units, or a combination comprising at least one of these. 
     
     
       8. The thermoplastic composition of  claim 1 , further comprising an ionizing radiation stabilizing additive. 
     
     
       9. The thermoplastic composition of  claim 8 , wherein the ionizing radiation stabilizing additive is an aliphatic alcohol, an aromatic alcohol, an aliphatic diol, an aliphatic polyol, an aliphatic ether, an ester, a diketone, an alkene, a thiol, thioethers, a cyclic thioether, a sulfone, a dihydroaromatic, a diether, a nitrogen compound, or a combination comprising at least one of the foregoing. 
     
     
       10. The thermoplastic composition of  claim 9  wherein the aliphatic diol has the structure:
   HO—(C(A′)(A″)) c —S—(C(B′)(B″)) d —OH 
 wherein A′, A″, B′, and B″ are each individually H or C 1 -C 6  alkyl; and wherein S is C 1 -C 20  alkyl, C 2 -C 20  alkyleneoxy, C 3 -C 6  cycloalkyl, or C 3 -C 6  substituted cycloalkyl; and wherein c and d are each 0 or 1, with the proviso that, where c and d are each 0, S is selected such that both —OH groups are not connected directly to a single common carbon atom. 
 
     
     
       11. The thermoplastic composition of  claim 1 , further comprising impact modifier, filler, antioxidant, heat stabilizer, light stabilizer, ultraviolet light absorber, plasticizer, mold release agent, lubricant, antistatic agent, pigment, dye, flame retardant, anti-drip agent, or a combination comprising at least one of these. 
     
     
       12. The thermoplastic composition according to  claim 11  wherein the additive is selected such that it does not significantly adversely affect the dYI of the thermoplastic composition after treatment with an ionizing radiation. 
     
     
       13. The thermoplastic composition of  claim 1 , wherein the aryl carboxylate end-capped polycarbonate includes aryl carboxylate end-capped homopolycarbonate, aryl carboxylate end-capped copolycarbonate, aryl carboxylate end-capped polysiloxane-polycarbonate, aryl carboxylate end-capped polysiloxane-co-(polyester-polycarbonate), aryl carboxylate end-capped poly(arylene ether)-co-polycarbonate, aryl carboxylate end-capped poly(arylene ether)-co-(polyester-polycarbonate), aryl carboxylate end-capped poly(alkylene ester)-co-polycarbonate, aryl carboxylate end-capped poly(alkylene ester)-co-(polyester-polycarbonate), aryl carboxylate end-capped poly(alkylene ether)-co-polycarbonate, aryl carboxylate end-capped poly(alkylene ether)-co-(polyester-polycarbonate), aryl carboxylate end-capped polyolefin-co-polycarbonate, aryl carboxylate end-capped poly(olefin)-co-(polyester-polycarbonate), or a combination comprising at least one of these. 
     
     
       14. The thermoplastic composition of  claim 1 , wherein the aryl carboxylate end-capped polycarbonate is benzoate end-capped poly(bisphenol-A carbonate). 
     
     
       15. A thermoplastic composition comprising:
 a polycarbonate that is not aryl carboxylate end-capped, and 
 an aryl carboxylate end-capped polycarbonate of formula:
   Ar 1 —C(O)—O-(-L-) m -O—C(O)—A 1   
 
 wherein each Ar 1  is independently an aryl group, -(-L-) m - is a polycarbonate linking group with m units of linking unit L, wherein L consists essentially of carbonate units where m is at least oen, or a combination of carbonate units with poly(arylene ether) units, soft block units, or a combination comprising at least one of these wherein m is 2 to 500 and at least one L is a carbonate unit; and 
 wherein the aryl carboxylate end-capped polycarbonate has aryl carboxylate end groups present in amount of 0.01 to 10 mole-percent based on the total number of moles of linking unit L present in the aryl carboxylate end-capped polycarbonate; and 
 wherein the aryl carboxylate end-capped polycarbonate is present in an amount of 1 to 80 wt %, based on the total weight of the polycarbonate that is not aryl carboxylate end-capped, and aryl carboxylate end-capped polycarbonate, with the proviso that the amount and type of aryl carboxylate end-capped polycarbonate used is selected so that the overall concentration of aryl carboxylate end groups is less than or equal to a molar concentration of 500 millimoles per kilogram (mmol/Kg), and is greater than or equal to 0.01 mmol/Kg, of the total weight of the polycarbonate that is not aryl carboxylate end-capped, and aryl carboxylate end-capped polycarbonate. 
 
     
     
       16. A method of preparing an aryl carboxylate end-capped polycarbonate, comprising condensing:
 a dihydroxy compound, 
 an aryl carboxylic acid halide, and 
 an activated carbonyl compound, 
 in a biphasic medium at a pH of about 9 to about 11, wherein the activated carbonyl compound is phosgene, diphosgene, triphosgene, a dichloroformate, or a combination comprising at least one of these, and wherein the aryl carboxylate end-capped polycarbonate has aryl carboxylate end groups present in an amount of 0.01 to 10 mole-percent based on the total number of moles of linking unit L present in the aryl carboxylate end-capped polycarbonate; and 
 wherein the dihydroxy compound and aryl carboxylic acid halide are pre-condensed at a pH of 7.5 to 11, and for a time of 1 to 60 minutes, prior to condensing with the activated carbonyl compound. 
 
     
     
       17. The method of  claim 16 , wherein the dihydroxy compound comprises a dihydroxy aromatic compound, a dihydroxy poly(arylene ether), a dihydroxy soft-block compound, or a combination comprising at least one of these. 
     
     
       18. The method of  claim 16 , wherein the aryl carboxylic acid halide is present in the biphasic medium in an amount of less than or equal to 10 wt % of the initial charge of aryl carboxylic acid halide. 
     
     
       19. The method of  claim 16  further comprising a phase transfer catalyst having the formula (R) 4 Q 30 X, wherein each R is the same or different, and is a C 1-10  alkyl group; Q is a nitrogen or phosphorus atom; and X is a halogen atom, a C 1-8  alkoxy group, or C 6-18  aryloxy group. 
     
     
       20. The method of  claim 16 , wherein the activated carbonyl compound is phosgene, wherein the dihydroxy compound is bisphenol-A, and wherein the aryl carboxylic acid halide is benzoyl chloride. 
     
     
       21. A method of making a thermoplastic composition comprising melt-blending:
 a polycarbonate that is not aryl carboxylate end-capped, and 
 an aryl carboxylate end-capped polycarbonate of formula:
   Ar 1 —C(O)—O—(-L-) m -O—C(O)—Ar 1   
 
 wherein each Ar 1  is independently an aryl group, -(-L-) m - is a polycarbonate linking group with m units of linking unit L, wherein L consists essentially of carbonate units wherein m is at least one, or a combination of carbonate units with poly(arylene ether) units, soft block units, or a combination comprising at least one of these wherein m is 2 to 500 and at least one L is a carbonate unit; 
 wherein the aryl carboxylate end-capped polycarbonate has aryl carboxylate end groups present in amount of 0.01 to 10 mole-percent based on the total number of moles of linking unit L present in the aryl carboxylate end-capped polycarbonate, and 
 wherein the aryl carboxylate end-capped polycarbonate is present in an amount of 1 to 80 wt %, based on the total weight of the polycarbonate that is not aryl carboxylate end-capped, and aryl carboxylate end-capped polycarbonate, with the proviso that the amount and type of aryl carboxylate end-capped polycarbonate used is selected so that the overall concentration of aryl carboxylate end groups is less than or equal to a molar concentration of 500 millimoles per kilogram (mmol/Kg), and is greater than or equal to 0.01 mmol/Kg, of the total weight of the polycarbonate that is not aryl carboxylate end-capped, and aryl carboxylate end-capped polycarbonate. 
 
     
     
       22. An article comprising the thermoplastic composition of  claim 1 . 
     
     
       23. A sterilization method comprising exposing an article to radiation wherein the article comprises a polycarbonate that is not aryl carboxylate end-capped, and
 an aryl carboxylate end-capped polycarbonate of formula:
   Ar 1 —C(O)—O-(-L-) m -O—C(O)—Ar 1   
 
 wherein each Ar 1  is independently an aryl group, -(L-) m  -is a polycarbonate linking group with m units of linking unit L, wherein L consists essentially of carbonate units wherein m is at least one, or a combination of carbonate units with poly(arylene ether) units, soft block units, or a combination comprising at least one of these wherein m is 2 to 500 and at least one L is a carbonate unit; 
 wherein the aryl carboxylate end-capped polycarbonate has aryl carboxylate end groups present in the thermoplastic composition in an amount of 0.01 to 500 mmol/Kg based on the combined weights of the polycarbonate that is not aryl carboxylate end-capped, and the aryl carboxylate end-capped polycarbonate. 
 
     
     
       24. The method according to  claim 23  wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of the aryl carboxylate end-capped polycarbonate, the polycarbonate that is not aryl carboxylate end-capped, and less than or equal to 1.0 percent total weight of aliphatic diol, a mold-release agent, and an antioxidant has, after exposure to a total gamma radiation dose of 81 kGy and when measured according to ASTM D 1925-70, an increase in yellowness index (dYI) of less than or equal to 24.5, when compared to the unexposed molded article. 
     
     
       25. The method according to  claim 23  wherein the aryl carboxylate end-capped polycarbonate is present in an amount of 1 to 80 wt %, based on the total weight of the polycarbonate that is not aryl carboxylate end-capped, and aryl carboxylate end-capped polycarbonate, with the proviso that the amount and type of aryl carboxylate end-capped polycarbonate used is selected so that the overall concentration of aryl carboxylate end groups is less than or equal to a molar concentration of 500 millimoles per kilogram (mmol/Kg), and is greater than or equal to 0.01 mmol/Kg, of the total weight of the polycarbonate that is not aryl carboxylate end-capped, and aryl carboxylate end-capped polycarbonate. 
     
     
       26. A thermoplastic composition comprising:
 a polycarbonate that is not aryl carboxylate end-capped, and 
 an aryl carboxylate end-capped polycarbonate of formula:
   Ar 1 —C(O)—O-(-L-) m -O—C(O)—A 1   
 
 wherein each Ar 1  is independently an aryl group, -(-L-) m - is a polycarbonate linking group with m units of linking unit L, wherein L consists essentially of carbonate units wherein m is at least one, or a combination of carbonate units with poly(arylene ether) units, soft block units, or a combination comprising at least one of these wherein m is 2 to 500 and at least one L is a carbonate unit, and m is at least one; and 
 an ionizing radiation stabilizing additive, 
 wherein the aryl carboxylate end-capped polycarbonate has aryl carboxylate end groups present in the thermoplastic composition in an amount of 0.01 to 500 mmol/Kg based on the combined weights of the polycarbonate that is not aryl carboxylate end-capped, and the aryl carboxylate end-capped polycarbonate, and 
 wherein a molded article having a thickness of 3.2±0.12 millimeters and consisting of the aryl carboxylate end-capped polycarbonate, the polycarbonate that is not aryl carboxylate end-capped, and less than or equal to 1.0 percent total weight of aliphatic diol, a mold-release agent, and an antioxidant has, after exposure to a total gamma radiation dose of 81 kGy and when measured according to ASTM D1925-70, an increase in yellowness index (dYI) of less than or equal to 24.5, when compared to the unexposed molded article.